Friday, November 30, 2018

The weather sucks...

and it is putting a major downer on rocket activities. This November in Huntsville has been unusually rainy, forcing the cancellation of the monthly launch and preventing me from making progress on my builds, which are still sitting in primer. I am seriously hoping that December will be drier, as I would like to finish off my Redstones and, you know, actually fly a few rockets at the club launch on the 8th. You hear that, weather gods? I really, really need to fly and make some headway, so clear dry days would be greatly appreciated. The current rain won't do at all.

I did take advantage of practically the only good day in recent memory to finish a couple of rockets and get the Mercury capsule painted. The first one to be completed was the Sky Bird II - an old Estes plan (#2) from the design book. It features break apart recovery by separating just below the bottom black stripe in the pic. The four color, pseudo native american decor was inspired by the stylized bird on the plan sheet, and I made the decals on my trusty ink jet. I think she turned out pretty well, and am looking forward to see this bird take flight at the next launch.

Sky Bird II (Click to enlarge).Sky Bird II plan sheet (Click to enlarge).
Next to roll off the assembly line was an Estes kit from the late 80's, the Lancer. An easy build, it makes a nice addition to my collection of kits that use the Estes Challenger/Generic fin can.

Estes Lancer (Click to enlarge).
Finally, I managed to paint the Mercury capsule, after struggling for hours trying to assemble that stupid escape tower. Doesn't seem to matter whether they are made of plastic or dowels, escape towers are a pain, especially for those of us with fat fingers. If you build one of these, I do suggest following Chris Michielssen's advice - assemble it from the top down, just like in the old Centuri instructions. After the paint dried, I applied a strip of red pin stripe tape around the capsule base, and it is now ready for the other markings.

Mercury capsule (Click to enlarge).
Waiting for some decent weather...

Tuesday, November 13, 2018

Working on Team Redstone...

My rocket ADD kicked in again, flaring up due to my seeing a lot of photos of models of Mercury Redstones, Gemini Titans, and Saturns recently. The 50th anniversary of Apollo 11 is coming up, so I reckon I should spend some time building replicas of the manned vehicles of the past - other projects are simply going to have to be put on hold. The U.S. journey into space started with vehicles based on the Redstone missile, so that will be the starting point. Specifically, the Jupiter-C that put the first U.S. satellite into space, Explorer 1.

Several years back, I wanted to try my hand at plastic model conversion (PMC), which is as it sounds. You find an appropriate model and add modifications such as body tubes, launch lugs, and ballast. The goal is for it to put in a stable flight, which is kinda tricky for some subjects. PMC is one of those "NASCAR-like" NAR competitions - people keep their heads down and lots of plastic parts litter the launch area. Given the prospects of disaster and my limited skills, I chose an easy subject - the Glencoe (formerly Hawk) Jupiter-C. Only cost about $15, and the instructions for the conversion were laid out 49 years ago by the G. Harry Stine himself (See the article by the Old Rocketeer here). I almost finished the model, with just the antennas left to be glued on, but got so disappointed in my poor assembly that I put it up on a shelf (I suck at plastic models, even though I built many as a boy. They looked awful - just like my rockets).

It sat on the shelf for years...

Converted Glencoe Jupiter- awaiting paint (Click to enlarge).
However, my Redstone mania this weekend actually gave me the impetus to pull it down off the shelf for an inspection. I was missing one of the antennas (which I could cannibalize from an unopened kit), and it looked like the application of a little Squadron putty could seal the cracks and joints caused by my poor assembly. This I did, and the model is now ready for paint. Now if I can only find the decals (may have to cannibalize them from the other kit as well).

So much for the Jupiter-C. Now on to my next subject, the Mercury Redstone. I have 4 of these kits in the stash - 2 of the 1921 genre and 2 of the 2167 "Liberty Bell" variety. It was easier to get at the Liberty Bell kits, so I picked one of those - a Hobby Lobby sale from way back.  I was kinda disappointed upon opening the bag - the lower tube with the fin slots was crushed, along with the coupler that joins the lower to the upper tubes. Plus, there were no instructions - how is that possible? Shaking my head, I printed off a new set of instructions from the Estes web site and set about fixing the lower tube with some ST-20 couplers (ain't no way I was going to try to cut those slots on a duplicate tube; my fingers are valuable to me). The old coupler was replaced with a new one from eRockets, and I mounted a Semroc EB-20 ejection baffle in the coupler for good measure. Should save me quite a bit of wadding on the flights.

Baffle mounted inside ST-20 coupler (Click to enlarge).
The tube spirals were filled and the tubes primed. I just finished assembling the motor mount and the capsule; still have the tower assembly to go. But first I need to get to the local hobby store and get the appropriate red and black paint. I'm hoping to do that sometime this week.

Two Redstones are not enough, so I also started work on their pappy, the Redstone missile. Recently I purchased a 3D printed Redstone fin can and nose from Boyce Aerospace; I had read excellent reviews about their products and wanted to use their stuff in my first build involving printed parts. The parts I received are most excellent, with nice detail. I would be doing a major happy dance except for one thing:

Pic showing the primed Redstone tubes, the unpainted Mercury capsule, the motor mount
along with the 3D printed Redstone fin can and nose from Boyce Aerospace. A Sky Bird II
(Estes rocket plan #02 from the Design Book) in white base coat is at left; behind it are
a clone of the Centuri Sky Devil in gray primer and an Estes Lancer in white primer (Click
to enlarge).
Like all 3D printed parts, they have rough surfaces - a product of the printing process.

Which means sanding...

LOTS of it...

Did I mention I hate sanding?

The Boyce parts came with instructions for assembling a scale model of the missile, specifying body tube lengths, CG location, and recommended motors. They also kindly provided a link to a YouTube video on how to get a smooth finish on 3d printed components. Guess what?

It shows a lot of sanding...

I am going to build this missile (which is the same scale as the Estes Mercury Redstone), even if I have to sand for a month. I have started with 220 grit on the nose, and will sand more this weekend. Hopefully I can have it done by Thanksgiving.

And that is what I have been doing rocket-wise on these rainy and cold November days.

Sunday, October 14, 2018

First HARA launch of 2018...

Warning! Many pics in this post!

Folks gathering around the RSO/LCO tents - Chris Short's trailer of wondrous rocket goodies is in the background
(Click to enlarge).
Yesterday's weather was perfect for flying rockets - mostly sunny skies, a light wind from the north, and afternoon temps in the mid-seventies. It was so nice and comfortable that I didn't even mind getting my aged carcass out of bed early to meet Allen for our 7:45 trip down to the new field. After a breakfast stop at Hardees, we arrived at the Butler Mill field near Woodville around 8:45. Chuck and Art were already in the process of setting up the range, which took till just past 10 AM. The first launch at a new location always starts out with a few issues and confusion - you have to figure out where to place the pads, work out where folks should park, etc. in addition to the normal launch set up. It'll go easier next time...

Looking towards the pads - I love this field! (Click to enlarge).
Art was instrumental in locating and getting permission for us to use the new field, so it was appropriate that his was the first rocket launched. Straight up into the blue, followed by a soft landing under parachute. Art's rocket set the pattern for the day - there would be many excellent flights, with not one drifting out of the field and only one - a model rocket - coming in ballistic.The launch pace was leisurely, with plenty of high power and model rockets taking to the air. I was surprised at the lack of mid power birds - we had some G flights, but I cannot think of a single F powered rocket that flew. Flyers started leaving the field around 3 - football is king in Alabama, and the games were summoning the faithful - so we closed up shop and left the field about 4. The 45 minute drive back to Huntsville went quickly, and I was uploading pictures to my computer by 5. Much better than the 2 hour trip back from the old field in Manchester!

Art's rocket under chute (Pic by Patrick; Click to enlarge).
The owner of the field is constructing an airfield on his property a little way from the corn field where we now fly. Soon after the launch began, we were started by the approach of two low flying airplanes, the second of which flew very, very low over the field just to the east of the range. So low that I was afraid it might crash when it banked away to the north east. Never before had this happened at a HARA launch, and we kept a close eye out throughout the rest of the day. I wonder if the pilots were a little wary of us, because scale models of AMRAAMs and Patriots were laid out on tables along the flight line, being quite popular with the attendees. The planes were so low they had to have seen them.

An airplane flies very low just east of the range (Pic by Patrick; Click to enlarge).
My list of some of the day's flights, in no particular order:

Allen flew his scratch-built scale cruise missile "Long Tom" on a K motor, achieving his NAR Level 2 certification. Congrats Allen!

Allen gets Long Tome ready for flight (Pic by Patrick; Click to enlarge).
Long Tom streaks skyward (Pic by Patrick;
Click to enlarge).
Long Tom under chute (Pic by Patrick;
Click to enlarge).
Elliot's high power Pike, Black Brant, and Darkstar Jr. rockets put in flawless flights. I was mostly interested in his modroc "fighter" collection - the Shrox fighter and the Odd'l Rockets F-104 did well, but the Odd'l Rockets F-16  had a recovery failure. Fortunately there was no significant damage after the dirt was cleaned out of the top of the body tube.

Elliot's Darkstar clears the rail (Click to enlarge).Elliot's fighter rockets at the RSO table
(Click to enlarge).
Patrick's 3D printed rockets - "Sign Here Please" and "Unclaimed Baggage" performed well, except that "Unclaimed Baggage" broke its nose cone when the main failed to deploy properly.

"Sign Here Please" and "Unclaimed Baggage" start their treks (Pics by Patrick; Click to enlarge).

As I said, there were a couple of AMRAAMs and Patriots on the field. The AMRAAMs were PML kits that flew on G and H white motors with apogee deployments - their owners got quite a bit of exercise. Jason flew his Patriot on a white, while Allen opted for an I212 smoky motor to power his model (he likes the dark plumes).

An AMRAAM takes to the sky on a G motor
(Click to enlarge).
Jason's Patriot rides a pillar of white fire
(Pic by Patrick; Click to enlarge).
A lightweight, minimum diameter 24 mm model made of carbon fiber that flew on an Aerotech E. This was a test flight before a mach busting attempt (using a G) to occur at Bama Blastoff in a couple of weeks.

2 flights of high impulse motors - Chris Short's "Gizmo" tore off the pad on an I599, whereas a small scratch built seemed to transport itself to 6000 feet on an H550 Super Thunder. I was surprised the latter held together, but it was obviously "built tough".

Michelle checks in at the RSO table (Click to enlarge).
Michelle's colorful scratch-built gets going
(Pic by Patrick; Click to enlarge).
The Oz rocket's motor ignites (Pic by Patrick;
Click to enlarge).
The Oz rocket deploys its parachute (Pic by Patrick; Click to enlarge).
Michelle and her dad launched a few scratch built modrocs and a mid power "tin man" themed Oz rocket on a G. Josh flew more model rockets than anyone - a Custom Ion Pulsar (which took a while to find among the harvested corn stalks), an Estes Air Show (one glider flew well, whereas the other tumbled to Earth), an OOP Estes 2127 Sizzler that came in ballistic when the rear-ejected pod broke away from the model, and repeated flights of a Comanche-3 in various configurations. The final flight was a D-C-C combo, which put the upper stage way, way up there. Fortunately, all stages were recovered, though the second stage required a bit of looking.

Josh hooks up his Ion Pulsar (Click to enlarge).
Josh's Estes Air Show on a C motor (Click to enlarge).Josh's Comanche-3 in motion (Pic by Patrick;
Click to enlarge).
Josh's Estes Sizzler leaves the rod powered by a Quest D16 motor (Click to enlarge).
I flew 4 rockets... First up was the Zoom Broom clone on an A3-4T. Good old Witch Hazel got her annual ride, ending with a comfy landing on the dirt. Next was the MPC X-2 Invader, featuring Marvin the Martian in its Looney Tunes decor. It was powered by a 1st gen Quest B4-4 Q-Jet, which required stripping off the motor label and a little effort to get it into the motor tube. Continuing the Halloween theme, my purple Target spider web candy bowl saucer made a short flight on an Estes C6-0. Finally,  a new Quest Q-jet C12-4 propelled my Big Bertha derivative, Beulah, containing a Jolly Logic Altimeter 3 to 427 feet. 

Witch Hazel rides her rocket (Click to enlarge).
Target candy bowl saucer on a C6-0 (Click to enlarge).The B4-4 Q-Jet in my MPC X-2 Invader leaves a trail
of black smoke (Click to enlarge).
Beulah descends under an orange parachute (Pic by Patrick; Click to enlarge).
Beulah's flight profile as recorded by the Jolly Logic Altimeter 3 (Click to enlarge).
That's this month's short summary... Can't wait for next month's launch!

Sunday, September 30, 2018

What I learned from this year's Geezer TARC...

I spent a lot of time with my designs and simulations this year. Here's what I took away from yesterday's launch:

Reliant's flight profile from the PNUT altimeter (Click to enlarge).
1) As expected, the simulated altitudes are overly optimistic, by tens of feet in my case. Reliant was predicted to go 874 feet; it actually flew to 801 feet, a difference of about 9%. In contrast, Artemis was simmed to 880 feet and flew to 871, a difference of only 9 feet. I'm thinking the latter is due to a set of fortunate circumstances, as the 9% is more in line with my expectations of a 10% difference in altitude. So if I was simming a TARC rocket, I'd select configurations that give altitudes about 70-100 feet above the goal (926 - 956 feet).

2) The online descent rate calculations did an excellent job predicting the descent rates - the choice of two 12" octagonal parachutes was perfect for egg capsules weighing close to 300 grams. I got measured rates of 22 and 23 feet per second, which are right on the money.

3) The BAMA Recovery Systems TARC parachutes took the stress, and they are octagonal, which increases the parachute drag. Plus they are lighter and cheaper than comparable Top Flight parachutes.

4) TARC teams using F32's in BT-70 rockets may be adding a fair amount of ballast this year to drop altitudes. Do lots of sims and choose your motors carefully based on the numbers. Watch the delay times - 6 seconds is close, 4 is way too short. Ejection should occur just past apogee, not before (as in the Reliant flight profile depicted above).

5) You can do this year's challenge on a cluster of 2 Estes E12-6's - Artemis' flight proved this. The question remains as to how consistent black powder clusters are from flight to flight. If you have to cluster, 2 motors are the easiest (naturally).

6) If you use the Perfectflite Firefly (cheaper, smaller, and lighter than the PNUT), get the field display unit. The flashing LED is tough to read on bright sunlit days.The Firefly is not a logging altimeter, but is kinda like the Jolly Logic Altimeter 2. Here's the data from Artemis' flight:
  • Apogee: 871 feet
  • Speed: 428 ft/sec
  • Time to Apogee: 7.4 sec
  • Flight Time: 44.6 sec
  • Descent rate: 23.4 ft/sec
  • FDD Battery: 3.06 V
  • FF Battery: 2.63 V
7) An "egg pusher" (BT-70 coupler bulkhead screwed to end of 18 inch 1/2" diameter wooden dowel) or something similar is a must if you are to get the eggs in/out without breaking them. 3 eggs are a pain to pack.

8) The Apogee egg cushions work well and are not that heavy. I flew the 2 egg cushion and a 1 egg cushion in each payload section.

9) Pack your parachutes very carefully - I used Estes wadding to keep the chutes separated in the body tube. You do not want the egg capsule parachutes tangling up - that would be bad.

That's what immediately comes to mind - hopefully some TARC teams find something useful in this post.

At long last...

In my previous post, I mentioned that the day was perfect for flying - clear skies, light wind, and comfortable temperatures. Soon after arriving at Pegasus, I realized that the latter was most definitely not true; low-to-mid eighties may seem not so bad when displayed on the screen of a cell phone, but experiencing them in the middle of a field puts quite a different perspective on the definition of hot. By the time the launch ended at 2 or so, I was panting like a rabbit after being chased by hounds. Sun block and water, my friends - bring them, use the former and drink the latter. They are your tickets to making it through a hot launch day.

Anyway, on to the launch...

Duane and I arrived at Pegasus about 11; folks were already there, including Fletcher Cannon, a new Geezer TARC participant, and Marc Loertscher, who won the contest a couple of years back. Marc was there to watch this year, and had brought along a young one to observe the anticipated carnage. Duane, Fletcher, Allen, and I proceeded to set up the range, and the other contestants - Patrick and Vince - showed up as we were putting things in place. All was ready to go around 11:30, by which time we had a nice crowd of family, local TARC team members, and UAH students settling in for the show. It was time to get some rockets airborne.

Allen's Cosmic Explorer starts the launch
(Click to enlarge).
Duane's Cherokee-D puts in yet another flight
(Click to enlarge).

Allen's modified Partizon on a CTI G83
(Click to enlarge).
Art Woodling's scratch leaves the pad on a D12-5
(Click to enlarge).
Allen started things off with his Estes Cosmic Explorer, which barely topped 300 feet riding an obviously defective F30 motor. A C6-7 put Duane's venerable Cherokee-D way up there, providing a good check on the wind direction despite a parachute failure; the rocket landed horizontally on the weeds, undamaged. Allen's modified Estes Partizon was up next on a CTI G83 Blue Streak reload. It reached an altitude of 1138 feet, and the dual deploy worked well, even though Allen forgot to reset the main deploy altitude to something appropriate for Huntsville (He last flew it at NARAM in Pueblo). Art was the last to fly before the Geezer TARC flights began. His scratch-built 24 mm powered rocket - the 1st rocket he flew with HARA - put in a flawless performance on a D12-5.

And now for the Geezer TARC flights...

Patrick with his 3D printed "Geezer III" (click to enlarge).
Patrick courageously went first, but his 3D printed orange Geezer III rocket had an igniter misfire. A new igniter was put into place, but the F22J reload seemed to have trouble getting going - it huffed a bit before coming to power, and the rocket only reached 488 feet altitude, far below the 856 foot goal. After the launch, I noticed that the picture sequence of the launch showed the igniter wires (and presumably the igniter) hanging on until the rocket had almost cleared the rail - that didn't help the performance. The good news is that the 3D printed model showed no signs of melting - which even Patrick expected - so Geezer III can fly again.

Sequence showing Geezer III dragging the launch cables with it (Click to enlarge).

Fletcher stepped up next, and his Saturn-decor rocket put in a very good flight. It soared to 906 feet and was down in just over 53 seconds - a solid 79 score, good enough to make me sweat even more in the midday heat.

The purple exhaust of the Blue Thunder motor in
Fletcher's rocket (Click to enlarge).
Fletcher's rocket clears the rail (Click to enlarge).
My turn had come - I placed the Reliant on the pad, hooked up the clips, and asked Duane to do the count and launch while I took pictures with my phone. All those hours of simulations and fretting over parachute sizing had come down to this moment, and I could only hope that my shaking hand would not mess up the launch pictures. Reliant, powered by an Aerotech F30FJ-6, rode a pillar of black smoke into the sky, its path straight and true, with no spin. Ejection occurred just past apogee, and I was relieved to see all three parachutes - two on the egg capsule and one on the sustainer - fully deploy. The egg capsule landed just a little over 41 seconds after launch, with the sustainer touching down about 20 seconds later. I was elated to hear the PNUT altimeter beep out a peak altitude of 801 feet, and even more excited when the eggs were confirmed to be without cracks. For the first time in Geezer TARC, I was in the lead, with a 62 score. Only Duane and Vince stood between me and victory, and even if one of them bettered Reliant's score, I still had my second entry, Artemis, waiting in the bullpen.

Reliant's F30FJ leaves a trail of thick black smoke (Click to enlarge).
Duane placed his entry on the pad. Painted blue with a gold nose, this rocket was a little smaller than mine, and had a finish a bit on the rough side, which he hoped would cause enough drag to offset the power of the loaded Aerotech F32-6T. His hopes were quickly dashed, as the rocket bulleted off the pad, almost disappearing in the blue of the sky. Clearly too high, but the amazing thing was that the egg capsule landed almost exactly 45 seconds after liftoff - a perfect time. Sure enough, the altimeter reported 1102 feet (the highest TARC flight of the day), so we were left scratching our heads as to how those eggs got down under two deployed 14" parachutes from that altitude in just 45 seconds total. At the needed descent rate of about 23 feet per second, it should have taken something like 55 seconds. I hope Duane will share his altimeter data, because inquiring minds want to know. Last year, Duane's flights were too low; this year's was too high, giving him a 254 score.

I was still in the lead, but the reigning TARC Geezer, Vince, the creator of Frankenstein rockets and shunner of simulations, was next. Would he neutralize all my scientific and engineering efforts with a thrown-together model and a randomly chosen motor from his stash? He had carefully kept his entry in his vehicle until this moment, and I was quite apprehensive as he approached the pad with this year's creation. The time of reckoning had arrived...

Vince's model surprised me by being a fairly conventional egg lofter. Painted white, with red fins, an orange transition, and a yellow nose, the rocket's egg capsule consisted of a length of ST-20 tube and the transition and nose cone from an old Estes Scrambler (the 1980's version) or Omelet Express.  The sustainer was based on Estes BT-60 tubing, with a 24 mm motor mount and swept fins. I had considered something similar back when the rules were announced in May, but abandoned the concept because of the limitations imposed by the BT-60 lower section. The lower weight and surface area (less drag) put this model in the twilight zone of motor choices - E's were not enough power, and F's were too much. You can only cluster up to 3 18 mm motors in a BT-60, and 3 C6's were not going to get the job done. So this design was not viable unless I was willing to cluster composites (3 AeroTech or Quest D's), and I am not yet crazy enough to try that with a trophy on the line.

Vince's rocket rides white fire up into the puffy clouds (Click to enlarge).
Vince's flight made me glad I tossed the design. His rocket was way, way overpowered on an Aerotech F44-8W, achieving a peak altitude of 1009 feet and a duration of 107 seconds. A 399 score, which meant I was the winner of Geezer TARC!

Vince holds this year's Skunk trophy (Click to enlarge).
Finally! I got the victor's trophy, and Vince, last year's winner, got the the Skunk trophy for the worst flight. After all, 1) his score was bad, and 2) his rocket was the only one to sustain damage, when the streamer on the sustainer failed to deploy. Cracked a couple of fins.

I was sorely tempted not to fly Artemis - I had won, it was hot, and I wanted some food - but the old girl beckoned to me from the car. So I loaded her up with eggs and a Firefly altimeter, and stuck 2 Estes E12-6's into the motor mount. I figured that these would provide enough power to get me close; 2 additional A or B motors would be risky, as simultaneously lighting 4 motors is no picnic. She quickly left the pad on a straight-up trajectory, with chutes deploying just past apogee. The egg capsule landed just over 45 seconds after liftoff - a perfect time - with the sustainer landing near the southwest corner of the field quite a bit later (24" parachute was too large). The Firefly display showed a peak altitude of 871 feet, just 15 feet too high. A 15 score - the best ever in Geezer TARC, and good enough for a qual attempt. I am very glad I flew Artemis!

The plumes from the dual E12's are visible as Artemis leaves the pad (Click to enlarge).
2018-2019 Geezer TARC scores (Click to enlarge).
Duane's Mammoth on an F52 (Click to enlarge).Josh's Nike-X powered by a C6-7 (Click to enlarge).

The launch lurched to an end soon after Artemis' flight - Duane flew his Mammoth on a F52, and there were a few model rocket flights. Around 2 we packed up and left the field. Upon arriving home, I placed my trophy on my rocket shelf, where it sits proudly. I am very pleased - to quote Mark Watney, "I scienced the sh*t out of this."

And it paid off.